Sicklefin Redhorse, Moxostoma sp.
Although the sicklefin redhorse is now known to have been collected in 1937 (based upon preserved specimens collected at the then un-impounded mouth of Forney Creek near its confluence with the Tuckasegee River), it was not recognized as a distinct species until 1992, the sicklefin redhorse is a medium-sized sucker, with a curved dorsal fin and a bright red tail. It is found primarily in the Hiwassee and Little Tennessee Rivers in Cherokee, Clay, Swain, Macon, and Jackson counties. The species has not yet been officially described and is relatively rare throughout its known range. The population is limited by the presence of dams and impoundments in the rivers and faces threats in the form of habitat loss and pollutants such as sediment.
The sicklefin redhorse, a freshwater fish species, can grow to a length of approximately 650 millimeters (roughly 25.6 inches). It has an elongate, somewhat compressed, body and a highly falcate (sickle shaped) dorsal fin (back fin). Its body is olive-colored, with a coppery or brassy sheen; its lower fins (pectoral, pelvic, and anal fins) are primarily dusky to dark, often tinted yellow or orange and pale edged; the caudal fin (tail fin) is mostly red; and its dorsal fin is olive in color, sometimes partly red. Based on an analysis of preserved specimens, the species is relatively long lived, with males of the species living at least up to 20 years of age and females up to at least 22 years of age.
The species is currently known to occupy cool to warm, moderate gradient creeks and rivers, and, during at least parts of its early life, large reservoirs. In streams, it is generally associated with moderate to fast currents, in riffles, runs, and well flowing pools and feeds and spawns over gravel, cobble, boulder, and bedrock substrates with no, or very little, silt overlay.
Like many other redhorse species, the sicklefin redhorse is known mainly from flowing streams; however, also like many other redhorse species, the sicklefin redhorse appears to have possibly adapted to spending at least part of its early life stages in the near shore areas of impounded streams. Current observations indicate that adults are year round residents of rivers and large creeks and that young, juveniles, and sub-adults occupy primarily the lower reaches of creeks and rivers and near shore portions of certain reservoirs. The currently impounded reaches no doubt provided habitat for adult sicklefin before they were impounded and could potentially/eventually again if the dams were removed. Currently, the dams are barriers to the species, preventing up and downstream expansion of the populations. This suggests that, while reservoirs may serve as maturation sites for sub-adult sicklefin redhorse, they do not provide suitable spawning, foraging, or winter habitat for adults of the species but rather are a factor limiting habitat for adult sicklefin redhorse.
Stomach analysis indicates that the sicklefin redhorse feeds on benthic macroinvertebrates (insect larvae, crustaceans, snails, etc.). When feeding, the species exhibits a well-defined preference for coarse substrates with abundant river weed. Studies indicate that river weed significantly enhances the abundance of benthic macroinvertebrates and has documented that post-spawning (i.e., the stream reach occupied following spawning and before migrating to deeper waters for the winter), the species typically relocates to stream reaches supporting high densities of river weed, where individuals appear to feed almost exclusively over river weed beds.
Spawning typically occurs over cobble, with usually only a small portion of sand and gravel, in moderate to fast flowing water in open areas and pockets formed by boulders and outcrops. Distinct from the foraging habitat, the species appears to spawn exclusively over coarse substrates lacking river weed. One study indicated the species begins upstream migration to spawning sites in late winter/early spring when water temperatures reach 10.0-12.0 degrees (º) Celsius (C) (50.0-53.6 º Fahrenheit [F]) and peak at water temperatures of 15.0-16.0 ºC (59.0-60.8 ºF). The species appears to exhibit strong spawning site fidelity, returning to the same stream and stream reach each year to spawn, possibly returning to their natal streams and spawning reaches similar to many salmonids.
Following spawning, the species appears to generally move down stream to deeper waters and more suitable foraging areas and to migrate further downstream to even deeper waters for the winter. Except during its migrations to and from spawning and wintering sites, the sicklefin redhorse appears relatively sedentary at its spawning, post-spawning, and wintering sites, travelling only short distances up and down stream within the occupied river reach; and, in addition to exhibiting strong spawning site fidelity, the sicklefin redhorse also appears to show a high degree of site fidelity to its post-spawning and wintering sites, returning to the same stream, and stream reaches each year.
In 2010, as part of the Tuckasegee Cooperative Stakeholders Team Settlement Agreement with Duke Energy, LLC, a small hydropower dam, the “Dillsboro Dam”, on the mainstem of the Tuckasegee River was removed and stream bank restoration within the former impounded river reach was carried out. It is hoped that this will allow for the expansion of Sicklefin redhorse back into upstream reaches of the river. The Service is working with Conservation Fisheries, Inc. (CFI), the NCWRC, and the Eastern Band of the Cherokee Indians (EBCI) to propagate the sicklefin
redhorse and reintroduce the species into currently unoccupied habitat within the species’ historic range.
In 2007 – 2010, juvenile sicklefin redhorse, reared by CFI from eggs collected from the Little Tennessee River stock, have been released into the Oconaluftee River above Ela Dam. In 2011, biologist s from WSNFH radio tagged juvenile fish to be monitored by researchers from Western Carolina University. Additional propagation and reintroduction efforts and population monitoring and studies of movement patterns, habitat use, and water quality requirements will continue with the assistance of WSNFH into the future as necessary and feasible. In addition, the Service has been working with biologists with the Tennessee Valley Authority; the states of North Carolina and Georgia; and, personnel with Roanoke College in Salem, Virginia and North Carolina State University in Raleigh, North Carolina and other partners to identify threats and other potential recovery measures for the sicklefin redhorse.
For more information about the sicklefin redhorse program, please contact Carlos Echevarria at 706-655-3382 ext. 1224 or firstname.lastname@example.org.